The trial of those charged with the murder of the indigenous leader Berta Cáceres Flores, which opens on Monday in Honduras, will be monitored by an international group of lawyers for possible violations of national and international standards.

Cáceres, the former Goldman prize winner for environmental defenders, was shot dead in her bedroom just before midnight on 2 March 2016 in La Esperanza, western Honduras, after a long battle to stop construction of an internationally financed hydroelectric dam on the Gualcarque River, which the Lenca people consider sacred.

Cáceres, the coordinator of the Civic Council of Popular and Indigenous Organizations of Honduras, was best known for her defence of indigenous territory and natural resources, but was also a respected political analyst, women’s rights defender and anti-capitalist campaigner.

Gustavo Castro, a Mexican environmentalist, was injured in the gun attack but survived by pretending to be dead.

The trial against the eight men accused of murdering Cáceres will be observed by lawyers from the US, Spain, Guatemala, France and Canada. The defendants are also charged with Castro’s attempted murder. They all deny the charges.

Cáceres led community opposition to the 21MW Agua Zarca dam, licensed to the company Desarrollos Energéticos SA (Desa).

Berta Cáceres speaks to people in January 2015 near the Gualcarque river in Honduras. Photograph: Tim Russo/AP

Her campaign triggered a wave of repression including smear campaigns, violent evictions and false criminal charges.

The licences and financing of the dam are subject to investigations by the Mission Against Corruption and Impunity in Honduras – an anti-graft group backed by the Organization of American States.

Desa denies any link with the murder and claims the company and its personnel have been wrongly targeted as a result of smear campaigns. “Slandering individuals before a trial in the name of human rights is a complete violation of their human rights,” said Robert Amsterdam, Desa’s lawyer.

In contrast, Cáceres’ family claim prosecutors have withheld crucial evidence to conceal a wider criminal conspiracy. A pre-trial ruling rejecting a petition to call members of the Desa board as witnesses suggests orchestrated bias, the family argue. The board includes members of the Atala Zablah family, part of one of the most powerful clans in Honduras.

Christine Wade, a professor of political science and international studies at Washington College, said: “What we’ve seen so far suggests the trial will obscure the intellectual authorship, and fails to shine a light on the rampant corruption in Honduras.”

Honduras is one of the world’s most dangerous countries in which to defend land and the environment, with at least 130 defenders killed since the 2009 coup ushered in a repressive, pro-business government that sanctioned mines and energy projects on rural and indigenous communities without consultation or adequate environmental impact studies. Prosecutions have been rare.

Two of the defendants are directly linked to Desa: Sergio Rodríguez Orellana, the company’s communities and environmental manager, and the US-trained former army lieutenant Douglas Bustillo, Desa’s security chief between 2013 and 2015.

Two others have military links: Mariano Díaz Chávez, an active US-trained special forces major with an intelligence background, and his former charge Henry Hernández Rodríguez.

A Guardian investigation found Cáceres appeared on a military hitlist targeting community leaders that was given to US-backed elite forces months before she was murdered.

The defendants Oscar Torres Velásquez, Elvin Rápalo Orellana and Edilson Duarte Meza are accused of participating in the shootings. Investigators found the alleged murder weapon in the house of Duarte Meza’s twin brother, Emerson Duarte Meza, who until then was not a suspect. Emerson Duarte Meza admitted illegal possession of a weapon, for which he was sentenced to three years in prison.

A similar gun found in the possession of Diaz was not subject to ballistics analysis until a recent court ruling ordered testing.

In March, a ninth suspect, Desa’s executive president, David Castillo Mejía, was charged with masterminding the crime. Castillo, a US-trained former intelligence officer, will face trial separately. Before her death, Cáceres told friends she was frightened of Castillo because of his military history. He denies any wrongdoing and told an initial hearing that he and Cáceres were friends.

The case will be heard by three judges and is scheduled to run in Tegucigalpa until 19 October.